Communication devices such as cellular radiotelephone devices are in widespread and common use. These devices are portable, and powered by batteries. One key selling feature of these devices is their battery life, which is the amount of time they operate on their standard battery in normal use. Consequently, manufacturers of communication devices are constantly working to reduce the power demand of the device so as to prolong battery life.
Some communication devices operate at a high audio volume level, such as those providing dispatch call capability. An example of such devices are those sold under the trademark “iDEN,” and manufactured by Motorola, Inc., of Schaumburg, Ill. These devices can operate in either a telephone mode, which has a low audio level for playing received audio signals in the earpiece of the device, or a “dispatch” or two-way radio mode where a high volume speaker is used. The dispatch mode is similar to a two-way or so called walkie-talkie mode of communication, and is substantially simplex in nature. Of course, when operated in the dispatch mode, the power consumption of the audio circuitry is substantially more than when the device is operated in the telephone mode because of the difference in audio power in driving the high volume speaker versus the low volume speaker. Of course, it would be beneficial to have a means by which the loudness of a speech signal can be enhanced without increasing the audio power of the signal, so as to conserve battery power. Therefore there is a need to enhance the efficiency of providing high volume audio in these devices.